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HTTP Basic Authentication

Definition: HTTP Basic Authentication is a simple challenge and response mechanism that involves sending a user name and password with requests to authenticate users with a web server. This information is usually encoded with Base64 to be transmitted over HTTP.

HTTP Basic Authentication is considered a vulnerable method for securing user credentials because the user name and password are only encoded, not encrypted. This encoding provides obscurity but can be easily decoded by anyone who intercepts the HTTP request. Consequently, HTTP Basic Authentication should only be used over secure connections, such as HTTPS, which ensures that the credentials are transmitted securely.

Furthermore, since HTTP Basic Authentication sends the same credentials with every request, it is susceptible to replay attacks unless additional security measures are implemented, such as the use of nonces and timestamps. It does not provide logout functionality or support for user sessions, and there are no built-in protections against brute force attacks. For these reasons, HTTP Basic Authentication is generally recommended only for simple authentication needs or for server-to-server communication where the connection can be secured, and the risks are well understood and managed.

The simplicity of HTTP Basic Authentication can lead to its use in testing environments or internal networks. However, more robust authentication frameworks like OAuth, OpenID Connect, or token-based authentication systems are recommended for applications requiring higher security levels.

What does HTTP Basic Authentication look like in practice?

Let’s say we want to send basic auth credentials to the website (These are not real credentials). We could use a curl request, such as:

curl -u "user:pass"

The resulting HTTP request looks like this:

GET / HTTP/1.1
Authorization: Basic dXNlcjpwYXNz
User-Agent: curl/8.4.0
Accept: */*
Connection: close

Key Characteristics:

  • Transmission of user name and password in Base64 encoding
  • Lack of inherent encryption, relying on HTTPS for secure transmission
  • Simplicity with minimal client and server resource requirements
  • Potential vulnerability to interception and replay attacks


  • Real-World Example: A developer testing a REST API may use HTTP Basic Authentication for simplicity, sending credentials over a secure connection with HTTPS, knowing the risks are minimal within a controlled environment.
  • Hypothetical Scenario: An old internal company system uses HTTP Basic Authentication for its minimal setup needs, with the understanding that access is restricted to the internal secure network and monitoring is in place to detect potential abuse.

Related Terms:

  • Base64 Encoding: The encoding method typically used to encode the credentials before sending them in an HTTP Basic Authentication header.
  • HTTPS: The secure version of HTTP that provides a secure channel over which HTTP Basic Authentication credentials can be safely transmitted.
  • Replay Attack: A potential risk when using HTTP Basic Authentication, where an attacker reuses intercepted credentials to gain unauthorised access.
  • OAuth: A more secure authentication protocol that could be used instead of HTTP Basic Authentication for more complex and secure authentication and authorisation requirements.

Learn better by watching a video? Here is a YouTube video explaining the concept.

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